Method for removing paraffin from oil wells, lines, tanks, pumps and the like



nite States Patent NIETHOD FOR REMOVING PARAFFIN FROM OIL WELLS, LINES,TANKS, PUMPS AND THE LIKE Albert J. Boyer, Kansas City, Kans.

No Drawing. Application June- 20, 1955 Serial No. 516,738

6 Claims. (Cl. 13440) This invention relates to the art of removingparafiin from equipment utilized in the production, transportation,storage or processing of petroleum products. More particularly, theinvention contemplates a simple method for removing such parafiin whichis both economical to perform and, in actual tests, has proven radicallymore effective in the accomplishment of the mentioned purpose than anymethod heretofore known.

The problem of formation of hardened parafiin on well tubes or casings,pipe lines, tanks, pump structures and the like, has long been one ofgreat seriousness and concern in the petroleum industry. Suchtroublesome formations of parafiin inevitably are deposited from certaintypes of petroleum upon everything with which such petroleum comes incontact during its recovery, transportation and storage. As successivelayers are deposited upon such surfaces, for instance oil well tubings,and as such deposits harden, impairment of the functioning of theapparatus upon which the deposits have accumulated obviously results. Inthe case of tubings, pipe or the like, a reduction in flow attended byback pressures and increased flow pressure requirements are encountered.In the case of pumps or the like, the deposits will, unless periodicallyremoved, eventually result in the equipment being rendered inoperative.

In the past, the most common method for removing paraffin from suchstructures has been by means of heat, usually in the form of steam, bywhich the paraflin is melted down to break the same loose from thesurface upon which it was deposited, followed by a flushing step inwhich water or the like may be used to remove the material so brokenloose. In the case of pumps, complete disassembly has usually beenrequired in order to properly accomplish the job, while in the case oflines it is normally required to disassemble and clean the linesection-by-section. The situation has been even more gravelydisadvantageous, if possible, in the case of well tubings where it hasheretofore been necessary to remove or pull the tubing from the well inorder to clean the tubing, as well as to get at the pump for cleaning ofthe latter.

It will be manifest that such procedures have been extremely expensiveand, except for the lack of a better method, quite impractical, in viewof the loss of the functioning time of the equipment occasioned by thenecessity for its removal or disassembly, as well as the considerableamounts of time and labor required to accomplish the paraffin removaleven after the equipment to be treated has been brought to a conditionof access for such treatment by removal from its normal location and/ordisassembly. Moreover, it will be evident that such methods heretoforenecessarily employed have required the provision of special andexpensive equipment at the place where the treatment is to be carriedout.

Accordingly, it is the primary object of this invention to provide amethod for the removal of paraflin from such structures and equipmentwhich will overcome the 2,937,112 Patented May 17, 1960 above-mentionedand other disadvantages and will make it possible for paraflin to beremoved from such equipment and structures without disassembly ordislocation thereof from their normal functional locations.

It is another important object of this invention to provide such amethod which may be carried out by relatively unskilled labor throughthe use of inexpensive materials and equipment normally available at awell site, and which will yield results either as good or better thanthose heretofore possible by the use of previous methods.

It is another important object of this invention to provide a method fortreating structures having a hardened deposit of parafiin thereon with amaterial adapted for removing such paraffin through settling thereofinto a liquid or suspended state by means of chemical action so thatsame may be removed from the structure along with the material when thelatter is withdrawn.

Still other important objects of this invention including the discoveryand identification of the material best adapted for use in performingthe method and the important conditions surrounding the performance ofthe method, will be made clear or become apparent as the followingdescription of the invention progresses.

The method of this invention generally contemplates the use of aparaffin settler or, in a somewhat loose sense, solvent which is appliedto a structural surface having a hardened deposit of paraflin thereon.Such application may be by spraying, painting, immersion, circulation orin other suitable fashion adapted to bring the solvent into contact withthe hardened deposit of paraifin for chemical action therebetween.

In the case of well tubings and pumps, such application may beaccomplished by simply introducing the material into the casing andpermitting same to remain therein for the required period, or afterintroduction of the settler or solvent material therein, the latter maybe circulated by means of the well pump or an auxiliary pump. One mannerof performing the method on the internal structure of oil wells whichhas proven quite effective has been to introduce the settler or solventmaterial into the well casing and then recirculate the same up throughthe tubing and pump, thence back down the casing of the well.

In the case of pipe lines, the material may simply be added to a productbeing passed therethrough or may be recirculated through a considerablelength of pipe line by means of an auxiliary pump and conduit tappedinto the pipe line at points considerably spaced from each other on thelatter.

In the case of pumps which are available on the surface of the ground,the method may be performed by simply filling the same with, orimmersing the same in, the settler or solvent material.

With respect to tanks and the like, a quantity of the settler or solventmaterial may simply be introduced into the tank or, if the size of thetank would render such procedure uneconomical, the material may besprayed, painted or otherwise suitably applied to the surfaces carryingthe hardened paraffin deposits.

Before proceeding to an explanation of the various conditions underwhich the method is preferably performed, attention is directed to thenature of the settler or solvent material to be used, which is in largemeasure of the essence in connection with the success of the overallmethod. The material currently preferred is prepared by combining asoluble oil composition including a rosin odeate, a mineral lubricatingoil and a coupling agent therefor with a petroleum solvent underconditions adapted to homogenize the same. A suitable water soluble oilcomposition is presently available from the Sinclair Refining Companyunder the trademark Satisol" and comprises as its material ingredientsaround 3% by weight of rosin odeate in a paraffin base type minerallubricating oil with a minor proportion of agent for coupling the odeatein the oil. The paraflin base lubricating oil contained in Satisol" hasthe following physical characteristics:

Gravity (API) 22-31. Flash point Min. 300 F. Firing point Min. 350 F.Viscosity (Saybolt Universal scale) 100350 seconds. Pour point 20 F.max.

The coupling agent employed is preferably an aliphatic type alcoholwhile the rosin odeate serves as the emulsifier. The completecomposition designated Satisol, has the following physical and chemicalconstants:

Gravity (API) 22-24.

Acid number 7.4.

Free fatty acid content 3.8% max. Ash 3.5% max. Water content Approx.2%.

The preferred proportion of the soluble oil composition, which it willbe obvious has the properties of an emulsifying agent by virtue of thepresence of the rosin odeate therein, with the petroleum solvent isabout 3 parts of the emulsifying soluble oil composition to 2 parts ofthe petroleum solvent, depending somewhat upon the particular solventused. The stated proportions will be found quite suitable where suchsolvent comprises #2 flame distillate or the like.

In preparing the settler material the soluble oil composition andpetroleum solvent are placed in proper proportions in a pressure mixturevessel and same are then subjected to blending sufficient to homogenizethe solution. It has been found that subjection of the soluble oilcomposition and solvent mixture to agitation by five thousandrevolutions per minute blades while under approximately 100 pounds persquare inch of pressure for a period of about 30 minutes is satisfactorywhere air agitators are also used, although it is to be understood thatsuch blending treatment may be carried on from about 20 minutes up toabout an hour as may be required for stabilization of the mixture inhomogenous condition.

Such settler or solvent material may be used either full strength ordiluted by the addition of kerosene, flame distillate or the likethereto at the point of use in proportions ranging up to about 5 partsof kerosene to 1 part of settler or solvent for fully satisfactoryresults. It will be obvious that the degree of dilution, if any, of thesettler or solvent material will depend to a considerable extent uponthe thickness of the deposited paraffin to be removed and the time overwhich the method is to be carried out. For all except the most extremecases, however, a mixture of about 3 parts of kerosene to 1 part ofsettler or solvent material is preferred and has been found to yieldsubstantially optimum results.

Again, the length of time during which the paraflin deposit to beremoved should be subjected to the settler or solvent material, is, inlarge measure, dependent upon the thickness of deposit. This may varywidely from about V2 to about 24 hours, with it being noted that duringthe latter named period a given quantity of the settler or solvent willnormally have fully performed that degree of action of which it iscapable. It is conceivable, therefore, that in a very extreme case, arepetitive treatment with a fresh quantity of settler or solventmaterial might be required, although such has not yet been encounteredin practice.

Although the exact nature of the chemical action which occurs betweenthe settler or solvent material and the hardened paraffin is not yetfully understood, the effect appears to involve the penetration andfimulsifi cation of the paraffin into a loosened, suspended and more orless liquid state in the settler solution. Such removed paraffin maythen be dumped, pumped, washed, or otherwise removed from the equipmentundergoing treatment.

It may be noted that the action of the settler or solvent material uponthe paraflin is substantially speeded if such material is circulatedrelative to the paraffin to be removed. Tests made on the Carlson No. 2well at Lindsborg, Kansas, have indicated that where the settler orsolvent material is circulated through the well tube or pump to betreated, a period of about 3 hours is satisfactory with a solution ofsettler material diluted with up to about 5 equal parts of kerosene orflame distillate. Similar tests performed at the Duval well No. 6 inWelch Pool in Rice County, Kansas, have indicated that subjection of apipe line to a 1 to 4 diluted solution of the settler or solventmaterial for a period of about 20 to 30 minutes resulted in decreasingthe pressure required for movement of petroleum through the lineapproximately in half, although such tests indicated that for completeclearing of the line of hardened paraffin the period of circulation ofthe settler material therethrough should be for a somewhat longer periodof the order of at least about 3 hours.

It has also been found that heating the diluted settler materialpreparation to approximately F. to F. speeds the chemical action of thepreparation upon paraffin. In a trial carried out at the facilities ofNational Supply Co. in Chase, Kansas, it was found that badly coatedpumps submerged in a preparation at said temperature of one part settlermaterial to three parts #2 flame distillate for approximately 30 minutescompletely removed all paraffin from the pumps.

Accordingly, it will be observed that the strengths and treating timesfor the removal of various thicknesses of hardened paralfin fromdifferent structures will depend to a fairly great extent upon suchthicknesses and the nature of such structures. It will be clear in anyevent, however, that the times and costs involved are radically lessthan those by which the same job of paraffin removal could possibly beaccomplished by methods heretofore known. The utility and advantages ofthe method will, therefore, be entirely manifest. Equally clear is thefact that the method contemplated by this invention involves an approachand solution to this problem along a dilferent line than has heretoforeeven been known or used.

Since certain aspects of the method can conceivably be varied and atleast some benefit still derived from utilization of the general conceptof this invention, it is to be understood that the invention should bedeemed limited within its fair breadth and intention only by the scopeof the appended claims.

Having thus described the invention, what is claimed as new and desiredto be secured by Letters Patent is:

1. The method of removing paraffin from a surface which comprisessubjecting the surface having paraflin thereon to contact with ahomogeneous mixture containing a Water soluble oil composition and #2flame distillate, said composition including a paraffin base lubricatingoil, rosin odeate and an aliphatic alcohol characterized by the propertyof coupling the rosin odeate into said lubricating oil and being presentin suflicient quantity to penetrate and emulsify the paraffin on saidsurface; then, removing said surface from contact with said mixture.

2. The method as set forth in claim 1 wherein said composition has anAPI gravity of 22 to 24, an acid number of 7.4, a maximum free fattyacid content of 3.8%, a maximum ash content of 3.5% and a water contentof approximately 2%.

3. The method as set forth in claim 1 wherein the parafiin baselubricating oil has an API gravity of 22 to 31, a minimum flash point of300 F., a minimum firing point of 350 F., a Saybolt viscosity of 100 to350 secends and a maximum pour point of 20 F.

4. The method as set forth in claim 1 wherein the References Cited inthe file of this patent rosin odeate is present in said composition inthe proportion of from about 2% to approximately 5% by weight. UNITEDSTATES PATENTS 5. The method as set forth in claim 1 wherein said1,415,605 Newbury May 9, 1922 mixture contains approximately 3 parts ofsaid composi- 5 1,722,211 Guardino July 23, 1929 tion to about 2 partsof said distillate by volume. 2,204,224 Limerick June 11, 1940 6. Themethod as set forth in claim 1 wherein said 2,358,665 Shapiro Sept. 19,1944 mixture is heated to a temperature between approximate- 2,442,100ShOWaIteI' May 25, 1948 1y 90 and 100 F. 2,613,186 Pickett Oct. 7, 195210 2,741,596 Luark Apr. 10, 1956

1. THE METHOD OF REMOVING PARAFFIN FROM A SURFACE WHICH COMPRISESSUBJECTING THE SURFACE HAVING PARAFFIN THEREON TO CONTACT WITH AHOMOGENEOUS MIXTURE CONTAINING A WATER SOLUBLE OIL COMPOSITION AND #2FLAME DISTILLATE, SAID COMPOSITION INCLUDING A PARAFFIN BASE LUBRICATINGOIL, ROSIN ODEATE AND AN ALIPHATIC ALCOHOL CHARACTERIZED BY THE PROPERTYOF COUPLING THE ROSIN ODEATE INTO SAID LUBRICATING OIL AND BEING PRESENTIN SUFFICIENT QUANTITY TO PENETRATE AND EMULSIFY THE PARAFFIN ON SAIDSURFACE, THEN, REMOVING SAID SURFACE FROM CONTACT WITH SAID MIXTURE.